This invention relates to a method of lapping webs and the product resulting therefrom and, more particularly, to webs which thereafter can be further processed as by zig-zag folding or rewinding.
In the aspect of the invention where the webs are zig-zag folded, such webs may be used for interfolded tissue and towel products having a pop-up feature. In the past, the ways of producing such interfolded products fell into two categories. One category involved the so-called continuous method where there were as many parent rolls as the count required in the retail package, i.e., for a 200 count package of tissues or towelling, more than 200 parent rolls were required. The extra parent rolls were required to compensate for the webs which may break during processing or when a given parent roll was exhausted and time required to replace it. Thus, producers face the prospect of over-compensating and very often a nominal 200 count package had 202, 203, etc. sheets therein. Where the number of parent rolls has been reduced as by deriving, for example, 10 webs from a single parent roll by slitting the wide roll, and thereby reducing the number of parent rolls to 20, the continuous feature is lost because parent rolls cannot be replaced on the fly under such circumstances. Additionally, the folds were produced longitudinally of the sheet length and the sheet was therefore dispensed in the cross machine direction of the paper machine which is usually considerably weaker than the strength of the web in the machine direction.
The other method of producing interfolded products used one or two parent rolls (or possibly twice as many parent rolls for two-ply products). Here the folds were produced transversely and the sheet dispensed in the stronger machine direction of the paper machine.
The instant invention falls in the second category where there have been historically two major types of folds and machines to produce them: (1) single fold, and (2) multi-fold. The single fold has the webs lapped one-half their length or alternatively can be considered a V-fold. The multi-fold, on the other hand, embodies three leaves of panels lapped one-third the length of the sheet and zig-zag folded so as to approximate a Z-fold.
Since the single fold machines made use of two parent rolls and the multi-fold only one parent roll, the productive capacity of the single fold machines have made these very attractive. In spite of this, the multi-fold product has enjoyed popularity, mainly because of the slim profile of its dispenser in public washrooms--the width being determined by the distance between folds, i.e., one-third versus one-half the sheet size.
The inventor hereof has tried for some 30 years to increase the output of the multi-fold machines by doubling the number of parent rolls to equal the single fold machines in production. The answer turned out to be in what the applicant chooses to call, in the preferred aspect, double three-leaf multi-fold. In explanation of this, it should be noted that the conventional three-leaf multi-fold is produced as shown by the inventor's prior U.S. Pat. No. 3,490,762 where one web, fed from a parent roll, is cut to desired sheet lengths, these sheets are then brought into an overlapping relationship and fed to zig-zag folding rolls. Although the U.S. Pat. No. 3,490,762 is of fairly recent vintage--being directed to a novel lapping means with accommodation for the slack produced the basic idea of three-leaf multi-folding is quite old, the first machine for this purpose on which the inventor hereof worked was built over 40 years ago.
The invention here concerns two parent rolls, each web being separately cut to discrete sheets, each web having its own lapping system and thereafter the lapped sheets from the two individual parent rolls are brought together in a staggered reverse relationship whereby all of the exposed edges face one direction. The combined webs can then be zig-zag folded as in the conventional system or, alternatively, rewound for sequential dispensing.